Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 7 Oct 2001 03:26:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 7 Oct 2001 03:26:18 -0400 Received: from postfix2-2.free.fr ([213.228.0.140]:16140 "HELO postfix2-2.free.fr") by vger.kernel.org with SMTP id convert rfc822-to-8bit; Sun, 7 Oct 2001 03:26:07 -0400 Date: Sun, 7 Oct 2001 09:21:05 +0200 (CEST) From: =?ISO-8859-1?Q?G=E9rard_Roudier?= X-X-Sender: To: Jes Sorensen Cc: , "David S. Miller" , , , Subject: Re: how to get virtual address from dma address In-Reply-To: Message-ID: <20011007091404.X953-100000@gerard> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 6 Oct 2001, Jes Sorensen wrote: > >>>>> "Paul" == Paul Mackerras writes: > > Paul> David S. Miller writes: > >> I can not even count on one hand how many people I've helped > >> converting, who wanted a bus_to_virt() and when I showed them how > >> to do it with information the device provided already they said "oh > >> wow, I never would have thought of that". That process won't > >> happen as often with the suggested feature. > > Paul> Well, let's see if we can come up with a way to achieve this > Paul> goal as well as the other. > > Paul> I look at all the hash-table stuff in the usb-ohci driver and I > Paul> think to myself about all the complexity that is there (and I > Paul> haven't managed to convince myself yet that it is actually > Paul> SMP-safe) and all the time wasted doing that stuff, when on > Paul> probably 95% of the machines that use the usb-ohci driver, the > Paul> hashing stuff is totally unnecessary. I am talking about > Paul> powermacs, which don't have an iommu, and where the reverse > Paul> mapping is as simple as adding a constant. > > I haven't looked at the ohci driver at all, however doesn't it return > anything but the dma address? No index, no offset, no nothing? If > thats the case, someone really needs to go visit the designers with a > large bat ;-( I would apply the bat to people that wants such a dma to virtual general translation. This thing is obviously gross shit. I would also apply the bat to people that look into stuff of other people and, instead of trying to actually understand the code, just give a look and send inappropriate statements to the list. G?rard. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/